Low Cycle Fatigue (LCF) is a failure mechanism that may limit the in-service life of turbine airfoils, such as blades. Cracks may be initiated by LCF in turbine airfoils after a number of engine cycles. High stresses may arise due to the geometry of the turbine airfoil. In ‘fir tree’ type couplings between a turbine disk and a turbine blade, these stresses often arise in the attachment fillets adjacent to (radially outboard of) the blade-disk bearing surface.